Today, many people across the political spectrum agree that the US and other Western democracies were wrong to severely restrict German Jewish immigration in the 1930s. This is so even though these governments were not responsible for the oppression of Jews in Nazi Germany. Moreover, we condemn 1930s US immigration policy despite the fact that, at that time, it was far from clear that Nazi anti-Semitism would culminate in mass murder on the scale of the Holocaust. Before World War II, only a very small number of German Jews were actually killed. The remainder were subject to extensive discrimination and repression. But in that respect they were probably no more than modestly worse off than many other discriminated-against minorities elsewhere in the world.

Despite this uncertainty, 1930s immigration policy was still deeply unjust. And one of the reasons why is that policymakers knew, or should have known, that German Jews faced a substantial risk of enduring still greater repression in the future, even if that outcome was not yet certain. By blocking most German Jewish immigration, the US and other western nations became partially complicit in the injustices inflicted against them. The US government was not just standing by and doing nothing in the face of Nazi oppression; it was using force to actively impede victims’ efforts to save themselves.

Economist Bryan Caplan extends this logic to other refugees fleeing oppression that hasn’t yet fully materialized. As he points out, German Jews in the 1930s are far from the only people trying to flee potential disaster who were prevented from doing so by immigration restrictions:

When disaster looms, governments routinely evacuate their citizens. At minimum, they urge them to leave the danger zone….

Evacuation policy blends humanitarian and pragmatic motives. If you care about people, getting them out of harm’s way is common sense. But even when governments feel little sympathy for disaster victims, they try to evacuate them anyway. As long as you’re under pressure to “do something” in the face of disaster, it’s vastly cheaper to prevent people from becoming disaster victims than it is to rescue them after they’ve already become disaster victims. Better still, evacuees foot most of their own rescue bill…. People who stay and lose everything, in contrast, are in no position to practice self-help….

[T]he moral and practical logic of evacuation doesn’t stop at national borders. (Logic rarely does). From a humanitarian point of view, letting people leave dangerous countries is only common sense. The fewer people who experience a disaster, the better. From a pragmatic point of view, moreover, allowing an anxious foreigner to emigrate at his own expense is far cheaper than bailing him out after tragic events leave him a desperate refugee….

In practice, of course, the world’s governments brutally discourage cross-national evacuation. Suppose you foresee natural or social disaster for your country. If you wisely try to get out Dodge, the world’s immigration restrictions dog you at every turn. Once disaster hits, you might be able to apply for refugee status. But as we’ve seen, that’s a long shot….

The root problem, of course, is that governments spurn the logic of international evacuation. Instead of encouraging non-citizens to leave dangerous countries post-haste, they impose deadly bureaucratic delays. And when a refugee crisis emerges, safe countries are shocked – shocked! – by the horror. Their complicity – the fact that their own immigration restrictions prevented the refugees from saving themselves back when there was still time – never enters their minds.

Bryan’s point has obvious applicability to the current refugee crisis facing Europe, which arose in part because Western nations were unwilling to accept more than a tiny number of Syrian migrants, until the humanitarian disaster reached truly epic proportions. It also applies to other similar cases.

Even if you don’t support a general presumption in favor of open borders migration, there is still a strong moral case for extending immigration rights to people fleeing repressive regimes and conflict zones where there is strong potential for much greater oppression in the near future. If we reject that position, we also have to conclude that 1930s restrictions on immigration by German Jews don’t deserve their bad reputation. After all, what the US and other western governments did at that time wasn’t much different from what many of the same nations routinely do today.

I do not claim that even the most desperate refugees should have absolute migration rights that always trump competing considerations. Just as I reject absolute property rights, and absolute rights to freedom of speech, I also reject an absolute absolute right to freedom of movement. In rare cases, the use of force to keep out refugees fleeing oppression may be the only way to avoid even greater horrors.

Allowing potential victims to flee oppressive regimes before disaster strikes won’t save all of them, or probably even most. Even if Western nations had more liberal immigration policies in the 1930s, many German Jews might have chosen not to leave, or been unable to emigrate for other reasons. The same is true of similarly endangered populations today. But the best should not be the enemy of the good. Liberalizing immigration policy in such cases is a great way to save many potential victims of oppression and mass murder, even if it cannot save them all.